Voltage regulator with thermostatic compensator



VOLTAGE REGULATOR WITH THERMOSTATIC COMPENSATOR Filed June 12, 1924 E Voifd e 602K INVENTOR. Bap/fir? 6 .Y we)? add W M WITNEfifiEAS' W ATTORNEY.

Patented Feb. 28, 1928 UNITED STATES PATENT OFFICE.

ANTON FRANK BROTZ, OF KOHLER, WISCONSIN, ASSIGNOR T KOHLER COMPANY, OF

KOHL'ER, WISCONSIN, A CORPORATION OF WISCONSIN.

VOL'IAGE REGULATOR WITH THERMOSTATIC COMPENSATOR.

Application filed June 12,

This invention has for its obj eat to provide means for automatically compensating for the variation in regulation that is due to the temperature of the solenoid windings in a voltage regulator such as that disclosed in my pending application for Letters Patent for voltage regulators, Serial No. 656,334, filed August 8, 1923.

The object of such regulators is to corre--. spondingly vary the speed of the generator with the variations in the load to maintain an approximately constant voltage.

With the above and other objects in view the invention consists in the voltage regulator with thermostatic compensator as herein claimed and all equivalents.

Referring to the accompan ing drawings. in which like characters of re erence indicate similar parts in difierent views,

Fig. 1 is a sectional view of a voltage regulatorfor generators constructed in ac cordance with this invention;

. Fig. 2 is a diagram showing a generator circuit including the voltage regulator;

Fig. 3 is a sectional view of one of the bimetallic thermostatic disks.

In the drawings, indicates a generator driven by an internal combustion engine, the throttle valve 11 of which is controlled by a solenoid having windings connected with the generator windings, as will be described. The generator vas shown is of the shunt type and supplies the mains 12 containing lamps 13 or other translating devices. The shunt field winding 14 of the generator is opposed by a bucking series field winding 15, which becomes stronger as the load on the mains increases and thereby opposes a greater influence to the shunt field to 1924. Serial No. 719,601.

weaken the field strength. At the same time a series coil 16, also in the load circuit and strengthened by the increasing load, opposes to a greater extent the influence ofa shunt or voltage coil 17 to effect a further opening movement of the throttle valve of the engine to increase the speed of the engine.

The solenoid is so constructed that the voltage coil 17 of many turns of fine wire connected in parallel with the shunt field 14 and the current or series coil 16 offew turns of large wire in the load circuit together act upon the core 21 but in opposition to each other. The solenoid core is pivotally connected to the shorter arm of a bell-crank lever 23, the other arm of which is connected by a link 27 with the throttle 1l.so that in the extreme upper position-of the core, as when the generator is not operating and the coils are therefore not energized, the throttle is held in an open position, as shown in Fig. 1. The core is held in this position by a coiled spring which affords a yieldin resistance to the operation of the solenoi core.

When the generator is started with a minimum loador no load on the service mains, the series coil 16 opposes the voltage coil 17 only slightly or not at all, and the core will be drawn to a lower position against the action of spring 25 and will move the throttle to a position partially closing the intake manifold of the engine, as shown by dotted lines in Fig. 1, so that the engine operates at a minimum speed under which the generator develops the line voltage. As the load increases the generator field is weakened by the bucking series field 15, as above mentioned, and the influence of the bucking current coil or series coil 16 becomes greater, tending to neutralize the influence of the voltage coil 17 and permitting the spring 25. to lift the core and move the throttle toward its open position, thus increasing the supply of fuel to the engine to incerase its speed corresponding with the increase in the load.

The proportioning of the field windings of the generator and of the coils of the solenoid and of the throttle and its operating means is made to compensate for a change in load by causing a chan e in speed without a material change in voltage the generator. The weakening of the generator field by the bucking coil 15 serves to developed by v facilitate the increasing of the speed of the engine caused at the same time by the bucking influence of the series coil 16 of the solenoidopening the throttle, and this bucking field winding exaggerates the speed variation characteristic of the generator for constant'voltage conditions so that the desired object is accomplished of materially reducing fuel consumption to correspond with a reduction of load.

For increased independent regulation a resistance is connected in series with the I shunt field winding 14 of-the generator and specti'vely,

wires 31 and 32 connect the ends of this resistance with switch contacts 33 and 34, re-

of a resistance short circuiting switch operated by a solenoid 50 which is connected across the terminals of the generator preferably with a resistance 51 in vseriestherewith. Thus the field regulating resistance short circuit is controlled by. a switch independent of-the throttle controlling solenoid' but sensitive to the variation in voltage developed by the generator. Be ing independent it is not afiected by the spring adjustments of the solenoid core.

I By this arrangement the momentary rise in voltage when the load is suddenly reduced from full load to minimum load is prevented, the sudden weakening of the buck ing current coil 16 accompanied by a slight strengthening 'ofthe voltage coil 17 being sufiicient to cause the core 21 to move to l the position for closing the throttle. At the same time the voltage coil 50, because of such-momentary rise in voltage, opens the contacts 33 and 34, thus breaking the short circuit around the regulating resistance 30 including this resistance in the shunt field winding to weaken the fields and check the rise in voltage. voltage is only momentary and as soon as the speed of the generator has reduced to correspond with the new throttle position, the normal conditions are restored, the throttle position being determined by the difierential solenoid 16-17 and the field" resistance short circuitin switch being perferret to and regulation is sufliciently I slightly mitted to close by the v0 tage coil 50.

As so far described the presentinvention is like that covered by my application for volta e regulators, Serial No. 656,334- refor all practical purposes. However, 1t may, under some conditions, be desirable to compensate for the variation in magnetic strength of the change in temperature thereof under operating conditions.

a positive temperature 'coefiicient, the predetermined regulation 7 voltage may be exceeded by a disproportional increase opening of the throttle due to the increased solenoid temperature under oper- Such tendency to abnormal close solenoid incident to the.

' When the solenoid coils are formed as usual of copper wire havlng a'ting conditions. -The temperature rise is not only due to the flow of current through the voltage coil 17 itself but to the heating influence of the bucking current coil 16 associated with it and carrying the load current. The increasing resistance of the voltage coil 17 results in a reduction in the current flow through it so as to diminish its value, in its tendency to close the throttle, and consequently the bucking current coil 16, aided by the spring 25, has a disproportionate influence in its tendency to open the throttle, resulting in the throttle being opened wider than itshould be for maintaining the predetermined regulating voltage under'the then existing load conditions with an accompanying slightly excessive speed of the engine and slightly excessive voltage.

The present invention providesthermostatic means sensitive to the changes in temerature of the solenoid for compensating or the weakening of the voltage coil when it becomes hotter by automatically reducing the effective pressure of the spring on the solenoid core, thus permitting of this temperature change taking place during a given load condition without alternating the position of the throttle.

The provision for reducing the effective spring pressure on the core as the solenoid becomes heated is shown in Fig. 1, wherein the core member 21 is directly ivotally .connected with the arm of bell-era 23 and the coiled spring 25 mounted on a fixed spring seat 60, which may or may not be adjustable, does not bear directly against the core but bears on a plunger 61 slidably fitting in a, bore of'the core in bearing against a column of thermostatic elements 62. These thermostatic elements 62 are preferably in the form of concave-convexsheet metal disks of bi-metallic thermostatic metal so curved that anincrease in temperature causes them to flatten and in the column they are alternately arranged so that their flattening tendency is cumulative, causing an effective shortening of the column with increasing temperature. This allows the plunger 61 to move farther into the bore of the solenoid core, consequently permitllt llt

tingthe spring to expand and reduce the 7 spring pressure against the core. The parts It isohvious that the thermostatic disks maybe arranged to increase their curvature with increasingtemperature or that other thermostatic elements may be employed to effect the compensation.

With thisinvention the predetermined voltage for the system is more closely maintained by compensating-for the weakening of the voltage coil from its increase in temperature so that changes in temperature may take place-without aflecting the speed of the engine.

What I claim as new and desire to secure by Letters Patent is: v Y

1. In a gas engine operated generating system, means for automatically varying the speed of the engine with the load comprising a solenoid having its winding adapted for connection with the generator winding and its core adapted for connection with the throttle, a spring acting on the core, and

a thermostatic means contained in the sole- I noid core for varying the position of the core with respect to its spring.

2. In a gas engine operated generating system, means for automatically varying the speed of the engine with the load comprising a solenoidhaving its winding adapted for connection with the generator winding and its core adapted for connection with the throttle, a thermostatic element carried by the core, and a spring bearing thereon.

3. In a gas engine operated generating system, a voltage regulator comprising a solenoid having its winding ada ted for connection with the generator win ing and its core adapted for connection with the throttle, a plunger slidably fitting in a bore of the core, a column of curved thermostatic disks contained within the bore of the core and engaged by the plunger, and a spring hearing on the plunger.

4. In a gas engine operated generating system, means for automatically varying the speed of the engine with the load comprising a solenoid having its winding adapted for connection with the generator wind-.

ing andits core adapted for connection with the throttle, and temperature-compensatin means sensitive to the temperature of the solenoid for varying the influence of the core. a

In testimony whereof, I afiix my signature.

ANTON FRANK BROTZ. 

